I don't know.... I think people get to offended to easily on price sometimes.
It's only worth what someone is going to pay. If you don't want the price that is offered than just say that. Doing the 'obo' thing is just opening the door for offers lower than what you are asking and then they get offended by it. Go figure. So why bother setting yourself up for that. Say the price is firm and be done with it. When it does not sell you'll have to lower the price if you want it gone.
Quoted from flynnibus:If you want to haggle... get a live conversation going.
Hard to do that if they won't respond.